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+/*
+ * Copyright (c) 2018 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/**
+ * @file
+ * @brief Unidirectional shared-memory multi-ring message queue
+ */
+
+#ifndef SRC_SVM_MESSAGE_QUEUE_H_
+#define SRC_SVM_MESSAGE_QUEUE_H_
+
+#include <vppinfra/clib.h>
+#include <svm/queue.h>
+
+typedef struct svm_msg_q_ring_
+{
+ volatile u32 cursize; /**< current size of the ring */
+ u32 nitems; /**< max size of the ring */
+ u32 head; /**< current head (for dequeue) */
+ u32 tail; /**< current tail (for enqueue) */
+ u32 elsize; /**< size of an element */
+ u8 *data; /**< chunk of memory for msg data */
+} svm_msg_q_ring_t;
+
+typedef struct svm_msg_q_
+{
+ svm_queue_t *q; /**< queue for exchanging messages */
+ svm_msg_q_ring_t *rings; /**< rings with message data*/
+} svm_msg_q_t;
+
+typedef struct svm_msg_q_ring_cfg_
+{
+ u32 nitems;
+ u32 elsize;
+ void *data;
+} svm_msg_q_ring_cfg_t;
+
+typedef struct svm_msg_q_cfg_
+{
+ int consumer_pid; /**< pid of msg consumer */
+ u32 q_nitems; /**< msg queue size (not rings) */
+ u32 n_rings; /**< number of msg rings */
+ svm_msg_q_ring_cfg_t *ring_cfgs; /**< array of ring cfgs */
+} svm_msg_q_cfg_t;
+
+typedef union
+{
+ struct
+ {
+ u32 ring_index; /**< ring index, could be u8 */
+ u32 elt_index; /**< index in ring */
+ };
+ u64 as_u64;
+} svm_msg_q_msg_t;
+
+/**
+ * Allocate message queue
+ *
+ * Allocates a message queue on the heap. Based on the configuration options,
+ * apart from the message queue this also allocates (one or multiple)
+ * shared-memory rings for the messages.
+ *
+ * @param cfg configuration options: queue len, consumer pid,
+ * ring configs
+ * @return message queue
+ */
+svm_msg_q_t *svm_msg_q_alloc (svm_msg_q_cfg_t * cfg);
+
+/**
+ * Free message queue
+ *
+ * @param mq message queue to be freed
+ */
+void svm_msg_q_free (svm_msg_q_t * mq);
+
+/**
+ * Allocate message buffer
+ *
+ * Message is allocated on the first available ring capable of holding
+ * the requested number of bytes.
+ *
+ * @param mq message queue
+ * @param nbytes number of bytes needed for message
+ * @return message structure pointing to the ring and position
+ * allocated
+ */
+svm_msg_q_msg_t svm_msg_q_alloc_msg (svm_msg_q_t * mq, u32 nbytes);
+
+/**
+ * Free message buffer
+ *
+ * Marks message buffer on ring as free.
+ *
+ * @param mq message queue
+ * @param msg message to be freed
+ */
+void svm_msg_q_free_msg (svm_msg_q_t * mq, svm_msg_q_msg_t * msg);
+/**
+ * Producer enqueue one message to queue
+ *
+ * Prior to calling this, the producer should've obtained a message buffer
+ * from one of the rings by calling @ref svm_msg_q_alloc_msg.
+ *
+ * @param mq message queue
+ * @param msg message (pointer to ring position) to be enqueued
+ * @param nowait flag to indicate if request is blocking or not
+ * @return success status
+ */
+int svm_msg_q_add (svm_msg_q_t * mq, svm_msg_q_msg_t msg, int nowait);
+
+/**
+ * Consumer dequeue one message from queue
+ *
+ * This returns the message pointing to the data in the message rings.
+ * The consumer is expected to call @ref svm_msg_q_free_msg once it
+ * finishes processing/copies the message data.
+ *
+ * @param mq message queue
+ * @param msg pointer to structure where message is to be received
+ * @param cond flag that indicates if request should block or not
+ * @return success status
+ */
+int svm_msg_q_sub (svm_msg_q_t * mq, svm_msg_q_msg_t * msg,
+ svm_q_conditional_wait_t cond, u32 time);
+
+/**
+ * Get data for message in queu
+ *
+ * @param mq message queue
+ * @param msg message for which the data is requested
+ * @return pointer to data
+ */
+void *svm_msg_q_msg_data (svm_msg_q_t * mq, svm_msg_q_msg_t * msg);
+
+#endif /* SRC_SVM_MESSAGE_QUEUE_H_ */
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */